WORCESTER, MASS. >> A security guard at a Worcester rooming house has been convicted of voluntary manslaughter for fatally shooting the facility's janitor.

Howard Penn had faced a charge of first-degree murder in the January 2014 shooting death of Lloyd Worster, but a 12-member Worcester Superior Court jury on Monday convicted the 56-year-old Penn of the lesser charge.

Penn faces up to 20 years in prison at sentencing scheduled for Wednesday.

Prosecutors say Penn shot the 52-year-old Worster in the back after a physical altercation in the security office at the Albion rooming house.

Defense attorneys say the shooting was in self-defense because Worster had threatened to kill Penn.

The Worcester Telegram & Gazette (http://bit.ly/2bRoEkL ) reports that Worcester's daughter called the verdict "absolutely ridiculous."

Information from: Telegram & Gazette (Worcester, Mass.), http://www.telegram.com